Noble Metal Single Atom Three-Way Catalyst for Exhaust Purification
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Solution Overview
Problem
Traditional three-way catalysts for motor vehicle exhaust purification face challenges such as high noble metal loading costs, temperature instability, and poisoning, leading to reduced catalytic performance and shortened service life.
Innovation Solution
A method for preparing a noble metal single-atomic three-way catalyst involves treating a noble metal precursor with a nitrogen-containing compound, followed by calcination, to achieve single-atomic dispersion on an oxide support, reducing impurity anions and preventing agglomeration, thereby enhancing stability and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of noble metals is increased to meet stringent emission regulations, then the catalytic performance is improved, but the cost increases and the utilization efficiency of noble metals decreases
Solution Approach 1:
The patent segments the noble metal from its traditional nanoparticle form into individual single atoms dispersed on the support surface. This segmentation allows each noble metal atom to function as an independent active site, maximizing the utilization efficiency of every atom while maintaining high catalytic performance with reduced noble metal loading
Solution Approach 2:
The patent changes the structural parameter of noble metal from nanoparticle scale (nanometers) to atomic scale (single atoms). This parameter change fundamentally alters the catalytic properties, enabling high activity with minimal noble metal quantity while improving cost-effectiveness
2Reliability
If noble metal nanoparticles are used as active components, then the catalytic activity is achieved, but the high-temperature resistance is poor leading to agglomeration and growth
Solution Approach 1:
By segmenting the noble metal into single atoms rather than nanoparticles, the patent eliminates the agglomeration and growth problems inherent in nanoparticle systems. Single atoms are inherently stable at high temperatures as they cannot aggregate further, while still providing catalytic activity through their isolated electronic structure
Solution Approach 2:
The patent introduces a support material as an intermediary that stabilizes the single noble metal atoms. The support provides anchoring sites that prevent atom migration and aggregation at high temperatures, while allowing the noble metal atoms to maintain their catalytic functionality
3Reliability
If noble metal nanoparticles are used as active components, then the catalytic function is provided, but the anti-poisoning capability is weak especially against sulfur
Solution Approach 1:
Segmenting the noble metal into single atoms increases the distance between adjacent metal atoms, reducing the ability of poison molecules (such as sulfur) to bridge multiple metal sites and cause deactivation. Isolated single atoms present fewer contiguous sites for poison adsorption, thereby improving anti-poisoning capability
Solution Approach 2:
Changing the noble metal structure from nanoparticles to single atoms fundamentally alters the interaction with poison molecules. The electronic and geometric parameters of single atoms differ from nanoparticles, resulting in weaker binding affinity for poison species and enhanced resistance to deactivation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method decreases noble metal loading by 30% while maintaining or exceeding the performance of traditional catalysts, improves high-temperature resistance, and increases anti-poisoning activity, effectively prolonging the catalyst's service life.
Implementation Method 1
The nitrogen-containing compound can realize the purpose of inhibiting the hydrolysis of the noble metal cation and stabilizing the noble metal single atom
Implementation Method 2
Step 2: calcining the catalyst precursor treated with the nitrogen-containing compound to obtain the noble metal single-atomic three-way catalyst
Implementation Method 3
By a three-way catalyst (TWC), the pollutants (HC, CO and NOx) emitted by motor vehicles will be catalytically converted into harmless gases such as carbon dioxide, nitrogen and water
Data Source
AI summary
The present invention relates to a preparation method for a noble metal single atom three-way catalyst, a catalyst obtained by using the method, and a use of the catalyst for purifying motor vehicle exhaust gas. In the present invention, a nitrogen-containing compound is used for treating a noble metal single atom catalyst precursor, avoiding the agglomeration of noble metal single atoms into nanocrystalline particles. The catalyst obtained by the preparation method of the present invention is resistant to high temperature, is not prone to agglomerate, and is resistant to poisoning, and the amount of usage of noble metals is reduced while the purification efficiency of the catalyst for motor vehicle exhaust gas is effectively improved.